Peter Zach

Peter Zach

I am a PhD student and psychologist currently working in National Institute of Mental Health in Prague. The main goal of my dissertation project is development of new event related potential (ERP) paradigms for assessing social cognition using more ecologically valid stimuli. Currently I am processing data from a new paradigm using N400 ERP as a correlate of social cognition in a serotonergic model of psychosis using psilocybin as an active compound. N400 is a negative component that appears approximately 400ms after the presentation of semantically unrelated information between two words or between word and context. Although this component is usually studied in the context of linguistic research, recent studies involved tasks combining videos of action sequences with image stimuli in social situations. My goal is to continue this line of research using videos and photographs as a stimuli in ERP paradigm to assess electrophysiological correlates of processes dealing with ability to evaluate appropriateness of emotional expression with regard to previous context during psilocybin intoxication.

Electrophysiological Correlations of Social Cognition: Event Related Potential N400 in Serotonergic Model of Psychosis Introduction

Dysfunctions of social cognition represent the central characteristic in a number of psychiatric disorders and critically affect their development and treatment. Furthermore these dysfunctions are the main causes of disability of affected individuals and impair their real life functioning in both the personal life and the working environment. Goal The aim of this work is to study the neurobiological correlates of social cognition in the serotonergic model of psychosis using event related potentials (ERPs). Psilocybin was selected as research compound. The specific parameter observed was the late event related potential N400. Methods A total of 20 healthy volunteers (10 women and 10 men) were included in the study. Inclusion criteria for the study were good general health status, negative psychiatric anamnesis and negative family psychiatric anamnesis with respect to the occurrence of psychoses. At the beginning of the measurement day, volunteers were given capsules containing the active substance (psilocybin) or placebo. Four hours after the drug was administered, volunteers completed the N400 paradigm. Videos of emotionally charged social interactions, followed by photos of the actor's face were shown on a projector in front of volunteers. The task of the volunteers was to assess the congruence between the emotional charge of the video and the emotional expression on the photographs. Results The results of the measurements have not yet been subjected to statistical analysis and were assessed only visually. Expected negative deflection in the 300-500 ms window following the presentation of the incongruent stimulus (N400) occurred only in the placebo group. The psilocybin group, on the other hand, showed an amplitude increase in the late positive component (LPC) 500-1000 ms after the presentation of the stimulus. Conclusion The results, due to the absence of statistical analysis, can be carefully interpreted as suggesting a different cognitive processing of social stimuli under the influence of psilocybin compared to placebo. It seems that psilocybin changes processes that allow us to understand social contexts in which we live. Further research can provide us with information about the influence of the serotonergic system on processes underlining social cognition.